For years, members of the New York City local 3 chapter of the International Brotherhood of Electrical Workers (IBEW) had enjoyed a lucrative contract with Time Warner Cable, which gave them particularly good healthcare and a generous 401(k), a retirement savings scheme.

But when Charter bought Time Warner Cable in May 2016, and absorbed it under its Spectrum cable and internet arm, that changed. Charter employs about 90,000 people across the US, and it wanted to switch Smythe and her ex-Time Warner Cable colleagues over to its boilerplate contract.

The union refused, and so started one of the longest strikes in recent history.

In an era where union membership has plunged to just 6.5% of private sector workers – a decline that some experts say influenced the Democratic party’s travails in the 2016 presidential election – the strike serves as something of a throwback to unions’ 1950s heyday, when 35% of the private sector was unionized.

Tanisha Smythe has been on strike for seven months. Photograph: Adam Gabbatt

Smythe, 35, was living in a homeless shelter in the Bronx with her young son when she got her job at Time Warner Cable. After starting at $12 an hour Smythe worked up to earning $19 an hour, before becoming a salaried field technician.

“Now I feel like I’m on the verge of going back to living homeless. And it’s a reality,” she said.

“Because even my son is like: ‘Are we going to be homeless soon?’”

The strike has attracted the attention of New York’s governor, Andrew Cuomo, and the New York City mayor, Bill de Blasio. The Democrats – both of whom are seeking re-election – appeared at a rally with the union members in downtown Manhattan in September, pledging their support. De Blasio has even offered to broker an agreement at City Hall. But so far, there has been no sign of Charter buckling.

The more than seven-month industrial action is an anomaly at a time when strikes, especially in the private sector, are rare. As is union membership.

Globalization hit traditionally unionized industries like steel and manufacturing in the 1980s, as companies began to build cars and other products abroad. As jobs were lost, union numbers dropped.

Alongside those economic changes, anti-union actions from companies hastened the decline, said Jake Rosenfeld, associate professor of sociology at Washington University-St Louis. “You see a real concerted and organized attack by employers who perfected an anti-union playbook,” he said.

Rosenfeld said some of those tactics include employing anti-union legal firms, which have become more popular, and firing union sympathizers, even though that is illegal. He said these tactics were rare when there was more union power in the US, but “they just became the norm relatively quickly”.

The impact of union decline can be felt throughout society – even in the 2016 presidential election, Rosenfeld said.

“They were not only economic organizations, they were political organizations. They provided the kind of manpower and a lot of the resources for largely Democratic political campaigns.”

In a recent article for the website On Labor, Rosenfeld argued that unions had once helped build coalitions of Democratic voters, in a similar way that evangelical churches and groups like the NRA now do with Republican voters. Without strong unions those coalitions have been lost.

“I do think that if you look at places where Trump performed particularly strongly, especially relative to Republican performances in elections past, these used to be really union strongholds.”

Some unions, however, are aligning themselves with policy issues important to workers and scoring victories.

National Nurses United, for example, has been a prominent part of the fight against the repeal of the Affordable Care Act. They mobilized to campaign for Bernie Sanders during the presidential election. Other unions have lent support to the Fight for $15 campaign for a federal minimum wage.

As for the dispute with Charter in New York, the company defended its package on offer to union members and blamed the IBEW for the strike.

“By keeping its members out of work, Local 3 is denying our employees a generous compensation package that includes an average 22%wage increase – some employees up to a 55% wage increase – and comprehensive retirement and health benefits, including a 401(k) that provides a dollar-for-dollar match up to 6% of eligible pay,” the company said in a statement.

Chris Erikson, business manager at Local 3, said the differences between the union and the Charter offer would have real consequences – particularly in healthcare, where the Local 3 plan offers exceptionally low premiums.

“The practical side of the medical plan that the members have is: my son had a kidney transplant and I got the bill from Columbia Presbyterian hospital and it was $96,000. My share of that was 200 bucks. If I was in Charter’s medical plan I’d probably have to take a loan to pay the hospital bill – that’s with coverage.”

Erikson, said “the union is not prepared to drop” but said he was aware that at some point individuals may decide to go back to work.

“We may lose if the membership or some group of people decide they’re gonna go back to work – I hate to say they’ll be going back without Local 3 – but this is something that the union is not prepared to accept.”

Union organizers, students, and supporters for a $15-an-hour wage march in Oakland. Photograph: Keith Srakocic/AP

Like the future of the strike, the future of unions in the US is also uncertain.

Union membership in the public sector has proved more robust than in private companies, with 34.4% of public sector workers enrolled in a union in 2016.

But those unions suffered a blow in Wisconsin in 2011, when Governor Scott Walker passed a law which damaged collective bargaining and the collection of dues, and worse may be yet to come.

In September the supreme court said it would hear an Illinois lawsuit that challenges whether public sector unions can collect fees from non-members, in a case that union leaders fear would drive down membership and reduce revenue.

“It’s hard to be overly optimistic at this point,” Rosenfeld said.

In the meantime, people like Smythe are clinging on, hoping to return to work soon.

Right now Smythe spends her time travelling to charities for food and hoping to get help to pay her mortgage. She spends three to four days on the picket line each week, but some days she struggles to leave the house. She finds it too depressing.

“I’m about to lose my home, I’m going to be probably evicted because I can’t pay my mortgage,” Smythe said.

“My son turned 10, his milestone birthday, no birthday party for him. He walks around saying: ‘Mom, I know you have to pay the bills so I don’t want a pizza or a hamburger, or to go to the restaurant to eat.’

“I can’t do mommy-son dates like we used to do. It’s not only affecting me. It’s affected him as well.”